Oil and natural gas are produced from wells having porous and permeable subterranean formations. The porosity of the formation permits the formation to store oil and gas, and the permeability of the formation permits the oil or gas fluid to move through the formation. Permeability of the formation is essential to permit oil and gas to flow to a location where it can be pumped from the well. Sometimes the oil or gas is held in a formation having insufficient permeability for economic recovery of the oil and gas. In other cases, during operation of the well, the permeability of the formation drops to the extent that further recovery becomes uneconomical. In such cases, it is necessary to fracture the formation and prop the fracture in an open condition by means of a proppant material or propping agent. Such fracturing is usually accomplished by hydraulic pressure, and the proppant material or propping agent is a particulate material, such as sand, glass beads or ceramic particles, which are carried into the fracture by means of a fluid.
In the course of production, oil and gas wells oftentimes exhibit scale formation and/or paraffin deposition that can reduce well production. Many types of chemical treatment agents have been used to prevent scale formation and/or paraffin deposition. One technique for delivering such chemical treatment agents downhole includes infusing porous ceramic proppant particulates with the chemical treat agent. In many instances, the chemical treatment agent must first be dissolved in an aqueous, organic or inorganic solvent to enable the infusion of the chemical treatment agent into the porous ceramic proppant particulates. If the chemical treatment agent is too viscous, however, this can result in lower effective amounts of the chemical treatment agent being present in the infused proppant than desired or uneven or ineffective infusion altogether. Dissolving the chemical treatment agent in the solvent is also an additional step that can be costly and time consuming.
Tracers have also been used in connection with hydraulic fracturing, to provide certain types of diagnostic information about the location and orientation of the fracture. Tracers for hydraulic fracturing have been associated with various carrier materials as particles from which the tracer itself is released after placement in the created hydraulic fracture. These tracer particles are oftentimes composed of a tracer substance and a carrier wherein the carrier is comprised of starch or polymeric materials. Carriers such as starch or polymeric materials are weak materials which if added to proppant in a hydraulic fracture can negatively affect conductivity. Further, the densities of starch or polymeric carrier materials are not similar to proppants typically used in hydraulic fracturing resulting in density segregation which can lead to non-uniform distribution of the tracer chemicals in the created fracture.
Therefore, what is needed is a method to add a chemical treatment agent to proppant particles without the need for a solvent. Also, what is needed is a tracer carrier that does not segregate from proppant when added to a subterranean environment and that does not negatively impact conductivity.